“pillarbox”

Change a Video Aspect Ratio Without Cropping Anything Out

There are exactly two ways to change an aspect ratio: throw pixels away or add space. Cropping 16:9 to 9:16 discards three quarters of the width, which is why so many auto-cropped verticals clip somebody's head. Letterbox and pillarbox padding keeps the frame, and the bars are an opportunity rather than a compromise.